Steam boiler



I 5 Sheets-Sheet 1. T. MAIN. STEAM BOILER.

(No Model.

Pam-tented Nov. 9, 1886.

Z Inventor N PEIERS. Phnlo-pum m hm, washingmn. I16.

(No Moglel.) 5 Sheets-Sheet 2. I T. MAIN.

STEAM BOILER. No. 352,142. Patented NOV. 9, 1886.

N. PETERS, Phamulho m hnn Washmglan. I10,

5 Sheets-Sheet 3.

m WWMWWM H Fi l III I 1 l n Patented Nov. .9, 1886.

T MAIN.

STEAM BOILER.

(No Model.)

NoQ. 352,142.

minesfias.

(m; Model.) 5 Sheets-Sheet 4.

T. MAIN STEAM BOILER. N0.,35 2,142. Patented Nov. 9, 1886.

N PETERS nowmnogn hu. Wilmington, u. c.

- uniform and predetermined pressure.

UNITED STATES PATENT Fries.

THOMAS MAIN, OF NEW YORK, n. Y.

STEAM-BOILER.

' rm SPECJ'IFICATION forming part of Letters Patent No. 352,142, dated November 9, 1886.

Application filed February 9, 1886. Serial No. 191,302 (hlo model.)

cityand county of New York, in the State of New York, have invented a new and useful- Improvement in Steam-Boilers, of which the following is a specification.

My invention relates to the class of steamboilers or steam-generators having furnaces which are closed, or from which the natural draft is excluded, and which are supplied with air by means of a pressure-blower or other aircompressing device for supplying air under a Ordinary coal, commonly employed for combusiion, contains twenty-five (25) per cent. (more or less) of hydrocarbons and free hydrogen, and in order to burn these elements it is desirable that air should be shut off from the ash-pit and admitted above the grate, while, when the fixed carbon of the coal is to be consumed, it is most desirable that air should be admitted through the grate. I have found that during one-third, (5 more or less, of the time between the intervals of charging a furnace the air should be shut off from the ash-pit and admitted above the grate, in order to consume the hydrocarbons and free hydrogen of the coal, so as to prevent carbonic-acid gas from ascending from the coal or coke on the grate and mixing with the hydrocarbons, while dur-' 'ing the remainder of the time between the charges of fuel air should be admitted below the grate, in order to burn the fixed carbon.

An .important object of my invention is to supply to a closed furnace theproper amount of heated air, both above and below the grate, in order to secure the most economical combustion ofthe fuel thereon.

My invention consists, essentially, in the combination, with a closed boiler-furnace having above the grate a hollow front, the inner wall of which is perforated, of a system of airpipes including an air-heater arranged in a connection or smoke-spaceof the boiler for delivering hot-air blast to the hollow furnace front and below the grate, and preferably, also, I valves for separately controlling the admission of air to the hollow front and to the ashpit below thegrate.

In the accompanying drawings, Figure 1 is a vertical longitudinal section of a marine boiler having the furnace below the boiler proper,and which embodies all the features of my invention. Fig. 2 is a horizontal section on the irregular plane of the dotted line or m, Fig. 3, which latter figure designates the boiler, one half in front elevation and the other half in vertical section uponthe plane of the dotted line 3 3 Fig. 1. Fig. 4 is a transverse vertical section on the plane of the dotted line zz, Fig. 1, and Fig. 5 is aside elevation of ordinary marine boilers with internal furnaces having my invention applied thereto. Fig. 6 is a front elevation of-such boilers. Fig. 7 is a vertical longitudinal section of an ordinary mnltitubnlar statio nary boiler, illustrating how my invention maybe applied thereto. Fig. 8 is a vertical transverse section on the plane of the dotted line Fig. 7. Fig. 9 is a horizontal sectionthrough the setting and a plan of-the boiler shown in Fig. 7. Figs. 10 and 11 are respectively a longitudinal section and my invention is applied; and Fig. 12 is a transverse section 011 the plane of the dotted line 8 s, Fig. 10.

Similar letters of reference designate corresponding parts in all the figures.

Referring first to Figs. 1, 2, 3, and4, A designates the boiler proper, which is or may be of cylindric form, and which contains heatingtubes ac, and is, as here shown, surmounted by a dome, A. The boiler and furnace are arranged within a casing or setting, which may be made of sheet or plate metal B, lined with fire-brick B.

O designates the furnace, and D the ash-pit having grate-bars c, and provided with suitable fire and ash-pit doors, cf 0 The setting 'has at the back a division-plate, deflector, or

partition, b, which extends to the rear end of the boiler below the uppermost tubes,a. When the boiler is in operation,the products of combustion pass under the bottom thereof to the rear, thence forward to the heating-tubes a to the first connection, d, thence rearward through the tubes a to the second or back connection, (1, and finally make their exit at the chimney opening or outlet 01", which is provided with a suitable damper, d

In order to catch sediment which may be deposited fromthe water in the boiler, I may employ a sediment-collector, E, which is composed of longitudinal sections hinged together at e, and which are of such width that when folded one on another they may bewithdrawn through the man'hole a? of the boiler. I thus provide for introducing into and removing from the boiler through the man-hole a scdiment-collector, which is broad enough when spread out to cover the principal portion of the bottom of the boiler. I do not claim this sediment-collector as included in this inven tion.

(2* designates the smokedoor at the front connection, (i.

For introducing air to the furnace, I employ a system oi pipes and an air-heater, which may be arranged in any connection or smoke passage or chamber of the boiler through which the products of combustion pass to the chimney-outlet d I have here shown a heator, F, composed of direct and return pipes or tubes arranged within the back connectiomd, from which the products of combustion pass to the chimney-outlet (I F designates a pipe which extends, as .here shown, from the front of the boiler rearward, and communicates with one end of the heater, and from the opposite end or outlet of the heater F a pipe,F extends forward again to the front of the boiler. The air to support combustion is supplied through the pipe F by a pressure-blower or other suitable air-compressing device or apparatus which is adapted to deliver an approximately uniform volume of air at a given pressure, and which is thereby distinguished from an ordinary fan-blower. What is known as the Root pressure-blower or a piston air-compressor, may be employed for this purpose.

In most or all cases it will be necessary to arrange the air-heater above the level of the grate, and hence a blower or air-compressing device will be necessary to produce the circulation of air through the heater. Such a blower is shown in Fig. 6, hereinafter described.

The pipe F' whereby the hot-air blast is delivered from the heater F, communicates with the furnace and ash-pit above and below the grate c. I have here shown the furnace above the grate as having a hollow front, G, the inner wall, 9, of which is finely perforated, and air introduced under pressure into the hollow front G will be delivered in numerous finejets or streams into the furnace above the fuel-bed therein. The pipe F, which extends forward from the air-heater F to the front of the furnace, communicates with a valve-box, F, (shown best in Figs. 2 and 3,) and this valve-box has a branch, f, which leads into the hollow front G, and .is controlled by a valve, f, and a second branch, f, which leads downward into the ash-pit belowthe grate, as best shown in Fig. 3, and is controlled by a valve, f. Immediately after introducing a fresh charge of fuel, I prefer to close the valve f controlling the supply of air-blast to the ashpit, and open the valve f, so as to deliver the air-blast into the hollow front G, and thence through the perforations in the inner wall, 9, thereof, in numerous fine jets or streams into the furnace above the fuel and grate therein. The air thus introduced will serve to burn the hydrocarbons and free hydrogen, and after these lighter combustibles have been consumed the valve f may be wholly or partially closed, and the valve f opened, so as to admit air below the grate into the ash-pit for burning the fixed carbon of the fuel. By this means I introduce just the proper quantity of air at the proper points to insure the best combustion and economical effects, and I avoid supplying to the furnace enough air to act injuriously in robbing it of its heat.

Thefurnace door or front may have a register or sighthole, it, as shown in Fig. 1, for the admission of natural draft, or to see the effect of opening or shutting the air-valves at every period in the combustion of the charge of fuel.

Referring now to Figs. 5 and 6, which represent marine boilers of the ordinary type having internal furnaces, H designates the breeching at the front of the boilers, from which the products of combustion pass to the chimney al in which is a damper, Around the chimney or stack I have represented a superheater, It. At the front of the boilers the fur naces are covered by a casing, 7t, in which are the fire-doors, and the grates are represented by dotted lines 0. Air is supplied to the cusing it through a pipe, F, from a pressure blower, I, and is admitted in regulated quantity, as may be desired, from the casing h" to the hollow perforated fronts of the furnaces, above the grates, and to the ash-pits below the grates, under control of valves or gates f f. The pipe F or part thereof may be conducted within the chimney (P, so that the air will be heated by the waste products of combustion. As here represented, the blower I takes its air through a suction-pipe, I, which may be connected with the cabins and holds of a vessel, so that the operation of the blower will not only supply forced blast to the furnaces, but will ventilate the vessel.

111 Figs. 7, 8, and 9 I have shown a common multitubular stationary boiler, A, set in a casing of brick-work, B, and having heating tubes a. G designates the furnace; D, the ashpit, and c the line of the grate. The furnace has a closed or hollow front, G, the inner wall, 9, of which is finelyperforated. The products of combustion from the furnace 0 pass rearward under the boiler, thence forward through the tubes a, and finally rearward over and around the upper part of the boiler to the chimney d In the smoke-passage, near the chimney, I have shown a pipe-heater, F, to which air may be supplied by a blower or other means through a pipe, F, and from the airheater a pipe, F leads to the front of the boiler and terminates in a valve-box, F, having branches f f, leading to the furnace and ash-pit above and below the grate, and controlled by suitable valves, as before described.

I regulated quantity above and below the grate.

In Figs. 10, 11, and 12 I have represented a locomotive'boiler, A, having heating-tubes a,

- a furnace, O, and ash-pit'D. The position of the grate is indicated by the dotted line 0. From the furnace O the products of combustion pass through the tubes a to the smoke box or chamber i, from which rises the smoke-stack (1 in which is a damper, 02 In the smokea box 1', I have represented a pipe air-heater, F,

to which the air is supplied by a blower or other compressing apparatus through a pipe, F, and from which the heated air is supplied through a pipe, F Near the front of the boiler the pipe 1? communicates with a valvebox, F having branches f f, controlled by valves or gates f f The furnace-door is in a casing, G,whioh is hollow, and has a perforated front wall, q, and the branch f leads to the casing G, and the branch f to the as h-pit D. By this system of pipes heated air may be supplied in properly-regulated quantity aboveand below the grate.

In order to secure the best results, it is necessary that provision should be afforded forshutting off entirely the supply of air to the furnace, either above the grate or below the grate, and also for introducing air both above and below the grate at times. In allthe examples of my invention pipes and valves are provided, whereby heated air may be shut off from the ash-pit'entirely immediately after a charge of fuel is introduced into the furnace,

and air supplied to the furnace abovethe grate only, and whereby the supply of air to the furnace abovethe grate may be shut off entirely and heated air supplied to the ash-pit only during the later period in the combustion of a charge of fuel.

What I claim as my invention, and desire to secure by Letters Patent, is

1.- The combination, with a closed boiler-furnace having above the grate a hollow front, the inner wall of which is perforated, of a system of air-pipes including an air-heater arranged in a connection or smoke-space of the boiler for delivering hot-air blast to the hollow furnace front and below the grate, substantially as herein described.

2. The combination, with the closed boilerfurnace having above the grate a hollow front, the inner wall of which is perforated,of a system of air-pipes including an air-heater arranged in a connection or smoke-space of the boiler for delivering hotair blast to the hollow furnacefront and below the grate, and valves for separately controlling the admission of hot air to the hollow front and below the grate, substantially as herein described.

THOMAS MAIN.

WVitnesses:

FREDK. HAYNEs, HENRY MCBRIDE. 

